There are several versions of toilet push buttons, so this may not apply to yours. I'm making the assumtion that the push buttons are on the ceramic cistern lid? This being the case you can either simply lift the lid off and the button will come away still attached to the lid or the lid won't easily lift off and is held down by the button. If the button is holding the lid down, you will need to grip the outer rim of the button housing and unscrew it counter-clockwise until it comes away. Either way you will probably find two threaded plastic prongs that are attached to each button which make contact with the flush valve inside the toilet cistern. To stop the buttons rising too high, adjust these prongs by screwing them clockwise a few turns which has the effect of shortening them and solving your problem.
Rupert
December 2019